WO2020158024A1

WO2020158024A1 - Battery pack, wireless power transmission system and hearing aid

Info

Publication number: WO2020158024A1
Application number: PCT/JP2019/033304
Authority: WO
Inventors: 創西尾; 太樹末吉; 尚津田; 真弥井上; 知起阿曽
Original assignee: 日東電工株式会社
Priority date: 2019-01-31
Filing date: 2019-08-26
Publication date: 2020-08-06
Also published as: JP2020123522A

Abstract

A battery pack 1 according to the present invention is provided with: a secondary battery 2 which has a positive electrode surface 13 and a negative electrode surface 14; a circuit board 20 which has a battery-side negative electrode terminal 45 that is electrically connected to the secondary battery 2; and a first lower adhesive layer 73 which bonds the negative electrode surface 14 and the battery-side negative electrode terminal 45 to each other. The first lower adhesive layer 73 contains a resin and a conductive filler that is dispersed in the resin. The first lower adhesive layer 73 has a tensile storage elastic modulus of 1 GPa or more at 23°C.

Description

Battery pack, wireless power transmission system and hearing aid

The present invention relates to a battery pack, a wireless power transmission system and a hearing aid.

↑ Conventionally, a rechargeable battery unit that can be charged wirelessly has been known. Such a secondary battery unit is highly convenient because it can be wirelessly charged using a corresponding charger while being attached to an electronic device.

As such a secondary battery unit, for example, Patent Document 1 discloses a battery pack. The battery pack described in Patent Document 1 includes a secondary battery including a battery negative electrode terminal and a battery positive electrode terminal, a circuit board including a battery side circuit positive electrode terminal and a charging circuit negative electrode terminal, and a coil member for receiving electric power. The battery side circuit positive electrode terminal is in contact with the battery positive electrode terminal, and the charging circuit negative electrode terminal is in contact with the battery negative electrode terminal.

JP, 2018-174123, A

In the battery pack described in Patent Document 1, the terminal of the circuit board is bonded to the electrode of the secondary battery with a conductive adhesive in order to improve the connection reliability between the electrode of the secondary battery and the terminal of the circuit board. To be considered.

However, since the secondary battery built in the battery pack repeatedly expands and contracts in the thickness direction (positive electrode-negative electrode direction) due to charge and discharge, the electrode of the secondary battery and the terminal of the circuit board are electrically connected by a conductive adhesive. When adhered, stress is applied to the conductive adhesive due to expansion of the secondary battery each time the secondary battery is charged and discharged.

The conductive adhesive secures conductivity by, for example, dispersing the conductive filler in the resin, and when stress is applied to the conductive adhesive, the dispersed state of the conductive filler in the resin may change. There is. Then, the electrical resistance of the conductive adhesive may fluctuate, and eventually the charging/discharging of the secondary battery may become unstable.

The present invention provides a battery pack, a wireless power transmission system, and a hearing aid that can ensure stable charging and discharging of a secondary battery while improving connection reliability.

The present invention [1] provides a secondary battery having a positive electrode surface on the upper surface and a negative electrode surface on the lower surface, a circuit board having a terminal electrically connected to the secondary battery, the positive electrode surface and/or An adhesive layer for bonding the negative electrode surface and the terminal is provided, the adhesive layer includes a resin and a conductive filler dispersed in the resin, and the adhesive layer has a tensile storage elastic modulus at 23° C. Includes battery packs of 1 GPa or more.

According to such a configuration, the adhesive layer that bonds the positive electrode surface and/or the negative electrode surface (hereinafter, referred to as an electrode surface) of the secondary battery and the terminal of the circuit board has a tensile storage elastic modulus of the above lower limit or more. Therefore, even if stress is applied to the adhesive layer due to expansion and contraction of the secondary battery, it is possible to prevent the dispersed state of the conductive filler in the resin from changing, and thus suppress the electric resistance of the adhesive layer from changing. ..

As a result, it is possible to improve the reliability of the connection between the electrode surface of the secondary battery and the terminals of the circuit board, while ensuring stable charging and discharging of the secondary battery.

The present invention [2] includes the battery pack according to the above [1], wherein the adhesive layer has a peel strength of 0.15 N/5 mm or more in a 90° peel test.

According to such a configuration, the adhesive layer has a peel strength equal to or higher than the above lower limit, so that the terminals of the circuit board are prevented from peeling from the electrode surface of the secondary battery even when the secondary battery expands and contracts. it can. Therefore, it is possible to surely improve the connection reliability between the electrode surface of the secondary battery and the terminal of the circuit board.

The present invention [3] includes the battery pack according to the above [1] or [2], wherein the adhesive layer has a thickness of 5 μm or more and 500 μm or less.

With such a configuration, since the thickness of the adhesive layer is not less than the above lower limit, it is possible to more reliably improve the connection reliability between the electrode surface of the secondary battery and the terminal of the circuit board. Moreover, since the thickness of the adhesive layer is not more than the above upper limit, the battery pack can be downsized.

The present invention [4] includes the battery pack according to any one of the above [1] to [3], wherein the adhesive layer has a volume resistance value of 1×10 ⁰ Ω·cm or less.

With such a configuration, since the volume resistance value of the adhesive layer is equal to or less than the above upper limit, efficient charge/discharge of the secondary battery can be ensured.

The present invention [5] includes the battery pack according to any one of the above [1] to [4], wherein the resin includes an epoxy resin.

With such a configuration, since the resin contains the epoxy resin, the tensile storage elastic modulus of the adhesive layer can be reliably adjusted within the above range.

The present invention [6] includes the battery pack according to any one of the above [1] to [5], wherein the content ratio of the conductive filler in the adhesive layer is 50 mass% or more.

According to such a configuration, since the content ratio of the conductive filler in the adhesive layer is equal to or more than the above lower limit, the tensile storage elastic modulus of the adhesive layer can be reliably adjusted within the above range, and the adhesive layer is electrically conductive. It is possible to surely impart the property.

The present invention [7] includes the battery pack according to any one of the above [1] to [6], wherein the conductive filler has a scaly shape.

According to such a configuration, since the conductive filler has a scaly shape, the conductive filler can be oriented in the direction orthogonal to the thickness direction of the adhesive layer, and the expansion and contraction of the secondary battery causes the adhesive layer to expand. Even if stress is applied, it is possible to reliably suppress fluctuations in the electrical resistance of the adhesive layer in the thickness direction.

The present invention [8] includes the battery pack according to any one of the above [1] to [7], wherein the conductive filler has an average maximum length of 30 μm or less.

However, if the average maximum length of the conductive filler exceeds the above upper limit, it is difficult to form the conductive path line because the conductive filler is less likely to contact the adhesive layer. Therefore, when stress is applied to the adhesive layer, there is a high probability that the conduction path cannot be established.

On the other hand, according to the above configuration, the average maximum length of the conductive filler is equal to or less than the above upper limit, so that the conductive state can be secured in the adhesive layer.

The present invention [9] is any one of the above-mentioned [1] to [8], further comprising a coil portion arranged on the upper side and/or the lower side of the secondary battery and electrically connected to the circuit board. The battery pack described in the above item is included.

According to such a configuration, since the coil portion electrically connected to the circuit board is provided, the coil portion can receive power from the external power transmission coil. Therefore, wireless power can be supplied to the secondary battery.

The present invention [10] includes a wireless power transmission system including the battery pack according to the above [9] and a power transmission device including a power transmission coil.

With such a configuration, the connection reliability is excellent, and a battery pack that can secure stable charging/discharging of the secondary battery is provided, so stable wireless charging of the secondary battery is possible.

The present invention [11] provides a battery pack according to the above [9], a hearing aid housing having a housing part for housing the battery pack, a microphone means, an amplification means, and a speaker part provided inside the hearing aid housing. And including a hearing aid.

With such a configuration, since the battery pack having excellent connection reliability and capable of ensuring stable charge/discharge of the secondary battery is provided, it is possible to suppress the occurrence of charging failure of the secondary battery.

The battery pack, the wireless power transmission system, and the hearing aid of the present invention can improve the connection reliability while ensuring stable charging/discharging of the secondary battery.

1A and 1B are perspective views of an embodiment of a battery pack of the present invention, FIG. 1A is a perspective view viewed from the upper side, and FIG. 1B is a perspective view viewed from the lower side. 2A-B are side sectional views of the battery pack shown in FIG. 1A. FIG. 2A is a sectional view taken along the line AA, and FIG. 2B is a sectional view taken along the line BB. 3A-B are development views of a substrate with a coil used in the battery pack shown in FIG. 1A. FIG. 3A is a plan view and FIG. 3B is a bottom view. FIG. 4 is a development view (the positive electrode terminal portion is omitted) of the coiled substrate shown in FIG. 3A. FIG. 5 is a sectional side view taken along line CC of the coiled substrate shown in FIG. 3A. FIG. 6 shows a partially enlarged view of a side sectional view of the coiled substrate shown in FIG. FIG. 7 shows an exploded perspective view of the battery pack shown in FIG. 1A. 8A to 8E are process diagrams of the method for manufacturing the battery pack shown in FIG. 1A. FIG. 8A is a process of bending a substrate with a coil, and FIG. 8B is a process of arranging an insulating resin sheet or the like in a partially bent circuit. 8C shows a step of preparing a first intermediate body and a spacer and the like, FIG. 8D shows a step of arranging the first intermediate body on a spacer and the like, and FIG. 8E shows a step of compressing and heating the first intermediate body. 9F-H are process diagrams of the method for manufacturing the battery pack shown in FIG. 1A, following FIG. 8E. FIG. 9F is a process for obtaining a second intermediate, and FIG. FIG. 9H shows the step of bonding to the battery, and the step of adhering the third intermediate body to the secondary battery. FIG. 10 shows a block diagram of an embodiment of the wireless power transmission system of the present invention. 11A-B show an embodiment of the hearing aid of the present invention, FIG. 11A shows a perspective view in an open state, and FIG. 11B shows a perspective view in a closed state. FIG. 12 shows a plan view (a form in which the positive electrode terminal portion has a through hole) of a modified example of the embodiment of the battery pack of the present invention. FIG. 13 shows a plan view of a modified example of the embodiment of the battery pack of the present invention (a mode in which the coil portion and the positive electrode terminal portion are arranged with a space). FIG. 14A is a graph showing the correlation between pressurization time and electric resistance in the reference example. FIG. 14B is a graph showing the correlation between the pressurizing time and the electric resistance in the reference comparative example.

Embodiments of the battery pack, wireless power transmission system, and hearing aid of the present invention will be described below with reference to the drawings. In FIG. 2A, the vertical direction of the paper is the vertical direction (first direction), the upper side of the paper is the upper side (one side in the first direction) and the lower side of the paper is the lower side (the other side in the first direction). In FIG. 2A, the left-right direction of the paper is the front-back direction (second direction orthogonal to the first direction), the right side of the paper is the front side (one side in the second direction), and the left side of the paper is the rear side (the other side in the second direction). ). In FIG. 2A, the paper thickness direction is the left-right direction (third direction orthogonal to the first direction and the second direction), the front side of the paper is the left side (one side in the third direction), and the back side of the paper is the right side (the third direction). The other direction). In FIG. 3A (developed view), the paper thickness direction is the thickness direction, and the front side of the paper surface is one side in the thickness direction and the back side of the paper surface is the other side in the thickness direction. Specifically, it is based on the directional arrow in each figure. By definition of these directions, there is no intention to limit the orientation of the battery pack, wireless power transfer system and hearing aid during manufacture and use. 3A-B and 4, the cover insulating layers (first coil cover insulating layer, second coil cover insulating layer, upper circuit cover insulating layer, lower circuit cover insulating layer) are omitted.

1. Battery Pack One embodiment of the battery pack of the present invention will be described with reference to FIGS. 1A to 9H. As shown in FIGS. 1A-B and 2A-B, a battery pack 1 according to one embodiment includes a secondary battery 2, a substrate with a coil 3, a magnetic sheet 4, an upper adhesive layer 5, a lower adhesive layer 6, and An insulating resin fixing portion 7 is provided. Hereinafter, these members will be described.

(Secondary battery)
The secondary battery 2 is a chargeable/dischargeable battery, has a substantially columnar shape (particularly, a button shape), and has a rectangular shape in side cross-section.

The secondary battery 2 includes a battery body 11 and a positive electrode tab 12. That is, the secondary battery 2 is a tabbed secondary battery.

The battery body 11 includes a battery positive electrode terminal and a battery negative electrode terminal.

The battery positive electrode terminal is arranged on the upper side of the battery body 11. Specifically, the battery positive electrode terminal is formed on the upper surface and the peripheral side surface of the battery body 11.

The battery negative terminal is located below the battery body 11. Specifically, the battery negative electrode terminal is formed on the lower surface of the battery body 11.

Specific examples of the battery body 11 include a lithium-ion secondary battery, a nickel-hydrogen secondary battery, and a silver-zinc secondary battery.

The positive electrode tab 12 is arranged on the upper side of the battery body 11 so as to come into contact with the upper surface of the battery body 11.

The positive electrode tab 12 is a flat plate having a substantially circular shape or a substantially annular shape in plan view. The upper surface of the positive electrode tab 12 has substantially the same shape as the upper surface of the battery body 11.

Examples of the material of the positive electrode tab 12 include conductive metals such as stainless steel, copper, silver, gold, nickel, tin and alloys thereof.

The positive electrode tab 12 is electrically connected to the battery positive electrode terminal of the battery body 11 and is fixed to the battery body 11 by a joining method such as welding (for example, spot welding).

With this, the upper surface of the secondary battery 2, that is, the upper surface of the positive electrode tab 12 becomes the positive electrode surface 13 of the secondary battery 2. On the other hand, the lower surface of the secondary battery 2, that is, the lower surface of the battery body 11 serves as the negative electrode surface 14.

(Substrate with coil)
In the battery pack 1, the coiled substrate 3 is arranged in the battery pack 1 in a bent state. That is, the coiled substrate 3 is incorporated in the battery pack 1 as a folding circuit 3A in the battery pack 1. First, the coiled substrate 3 before being incorporated into the battery pack 1 will be described with reference to the developed views shown in FIGS. 3A-B and FIGS. 4-6.

The board with coil 3 is a flexible printed circuit board having flexibility and integrally includes the circuit board 20 and the coil portion 60. That is, the battery pack 1 includes the circuit board 20 and the coil portion 60.

The circuit board 20 includes a control unit 21, a battery-side terminal unit 22, a positive electrode terminal unit 23, a negative electrode terminal unit 24, a first connecting unit 25, a second connecting unit 26, and a third connecting unit 27. Prepare integrally.

The control unit 21 is a main unit on which a control element 32 for controlling charging/discharging is mounted, and is arranged substantially in the center of the circuit board 20 in plan view. The control unit 21 has a substantially circular shape in plan view and is formed to be slightly smaller than the secondary battery 2 in plan view.

The control unit 21 includes a control circuit board 31 and a control element 32.

The control circuit board 31 is a wiring circuit board on which the control element 32 is mounted. The control circuit board 31 includes a control circuit base insulating layer 33 and a connection wiring pattern 34 in the thickness direction.
In the control circuit board 31, the surface on which the control element 32 is mounted (the surface visible on FIG. 3A, one surface in the thickness direction) is the mounting surface, and the opposite surface (on the side visible on FIG. 3B). The surface, the other surface in the thickness direction) is the back surface.

The control circuit base insulating layer 33 forms the outer shape of the control unit 21 and has a substantially circular shape in plan view. The control circuit base insulating layer 33 is formed in a sheet shape from an insulating material (described later). Note that in this specification, the insulating layer refers to a layer formed of an insulating material in a sheet shape.

The control circuit base insulating layer 33 has via portions (first to third portions) for electrically connecting the connection wiring pattern 34 and the control element 32 (a rectifier 38, a charge controller 39, a transformer 40 described later). A plurality of via portions 35 to 37) are formed. Specifically, a plurality (four) of first via portions 35 for connecting to the rectifier 38, a plurality (three) of second via portions 36 for connecting to the charging controller 39, and a transformer 40. And a plurality of (three) third via portions 37 for connecting with the. In each via portion (including via portions such as fourth to fifth via portions described later), a via opening portion that vertically penetrates a base insulating layer such as the control circuit base insulating layer 33 is formed. A metal conductive portion is filled in the via opening.

A part of the connection wiring pattern 34, specifically, a first connection wiring 34a to a ninth connection wiring 34i described later are arranged on the back surface of the control circuit base insulating layer 33.

The control element 32 is an element that controls the power flowing through the connection wiring pattern 34 during charging and discharging, and is mounted on the control circuit board 31. The control element 32 includes a rectifier 38, a charge controller 39, and a transformer 40.

The rectifier 38 is an element (AC/DC converter) that converts AC transmitted from the coil unit 60 into DC during charging. The rectifier 38 is arranged on the rear side of the mounting surface of the control circuit board 31. The rectifier 38 is electrically connected to the first connection wiring 34a, the second connection wiring 34b, the third connection wiring 34c, and the fourth connection wiring 34d via the first via portion 35.

The charge controller 39 is an element that controls the electric power converted into direct current by the rectifier 38 and transmits the electric power to the battery side terminal portion 22 during charging. The charge controller 39 has a communication function of, for example, monitoring the charge state of the secondary battery 2 to generate a communication signal and transmitting the signal to the power transmission device 81 (described later), if necessary. The charge controller 39 is arranged on the front side of the mounting surface of the control circuit board 31. The charge controller 39 is electrically connected to the third connection wiring 34c, the fifth connection wiring 34e, and the sixth connection wiring 34f via the second via portion 36.

The transformer 40 is an element for adjusting the voltage from the secondary battery 2 during discharging. The transformer 40 is arranged on the right side of the mounting surface of the control circuit board 31. The transformer 40 is electrically connected to the seventh connection wiring 34g, the eighth connection wiring 34h, and the ninth connection wiring 34i via the third via portion 37.

The battery-side terminal portion 22 is a battery-side positive electrode terminal portion for joining with the positive electrode surface 13 of the secondary battery 2. Specifically, the battery-side terminal portion 22 is a terminal for supplying the current from the coil portion 60 to the positive electrode surface 13 of the secondary battery 2 at the time of charging, and the positive electrode surface 13 at the time of discharging. Is a terminal for supplying a current from a positive electrode terminal (for example, an external device positive electrode terminal 96 described later) of an external electronic device (for example, a hearing aid 90 described later) via the positive electrode terminal portion 23.

The battery-side terminal unit 22 is arranged on the left side of the control unit 21 with a space from the control unit 21. The battery-side terminal portion 22 has a substantially rectangular shape in plan view.

The battery-side terminal portion 22 includes a battery-side terminal base insulating layer 41, a battery-side positive electrode terminal 42, and a connection wiring pattern 34. In the battery-side terminal portion 22, the surface on the side where the battery-side positive electrode terminal 42 is exposed (the surface visible on FIG. 3A) is the terminal surface, and the opposite surface (the surface visible on FIG. 3B). Is the back side.

The battery-side terminal base insulating layer 41 forms the outer shape of the battery-side terminal portion 22 and has a substantially rectangular shape in plan view. A plurality of (two) fourth via portions 43 for connecting to the positive electrode terminal portion 23 are formed in the battery-side terminal base insulating layer 41. The two fourth via portions 43 are formed so as to overlap the battery-side positive electrode terminal 42 when projected in the thickness direction.

The battery-side positive electrode terminal 42 is arranged substantially in the center of the battery-side terminal portion 22 in plan view so as to be exposed from the terminal surface of the battery-side terminal portion 22. The battery-side positive electrode terminal 42 has a substantially circular shape in plan view.

A part of the connection wiring pattern 34, specifically, a fifth connection wiring 34e and a seventh connection wiring 34g described later are arranged on the back surface of the battery side terminal base insulating layer 41.

The positive electrode terminal portion 23 is an external positive electrode terminal. That is, the positive electrode terminal portion 23 is a terminal for supplying the current from the secondary battery 2 to the positive electrode terminal of the external electronic device during discharging.
It should be noted that in the positive electrode terminal portion 23, the surface on the side that contacts the positive electrode terminal of the external electronic device (the surface visible on FIG. 3A) is the contact surface, and the surface on the opposite side (the surface visible on the side in FIG. 3B). Is the back side.

The positive electrode terminal portion 23 is arranged on the rear side of the control portion 21 with a space from the control portion 21. The positive electrode terminal portion 23 has a substantially circular shape in a plan view and is formed to be slightly smaller than the control portion 21. The positive electrode terminal portion 23 is formed of a conductive metal supporting plate described later.

The negative electrode terminal portion 24 is an external negative electrode terminal and a battery negative electrode terminal. That is, the negative electrode terminal portion 24 is a terminal for supplying the current from the coil portion 60 to the negative electrode surface 14 of the secondary battery 2 at the time of charging, and the current from the negative electrode surface 14 at the time of discharging to the external electronic device. This is a terminal for supplying the negative terminal of the device. It should be noted that in the negative electrode terminal portion 24, the surface on the side that contacts the negative electrode terminal of the external electronic device (the surface visible on FIG. 3A) is the contact surface, and the surface on the opposite side (the surface visible on FIG. 3B). Is the back side.

The negative electrode terminal portion 24 is arranged on the front side of the control portion 21 with a distance from the control portion 21. The negative electrode terminal portion 24 has a substantially circular shape in plan view and is formed to be slightly smaller than the control portion 21.

The negative electrode terminal portion 24 includes an external negative electrode terminal 44 and a battery negative electrode terminal 45 as an example of a terminal in the thickness direction. That is, the circuit board 20 includes the battery-side negative electrode terminal 45.

The external negative electrode terminal 44 is arranged on the contact surface side of the negative electrode terminal portion 24. The external negative electrode terminal 44 has the outer shape of the negative electrode terminal portion 24 and has a circular shape in plan view. The external negative electrode terminal 44 is formed of a conductive metal supporting plate described later.

The battery-side negative electrode terminal 45 is arranged on the back surface side of the external-side negative electrode terminal 44, and has substantially the same shape as the battery-side negative electrode terminal 45 in a plan view. The battery-side negative electrode terminal 45 is made of the same material as the connection wiring pattern 34.

The first connecting part 25 connects the control part 21 and the battery side terminal part 22 and is arranged on the left side of the control part 21. Specifically, the first connecting portion 25 is arranged between these so that the right end thereof is continuous with the control portion 21 and the left end thereof is continuous with the battery side terminal portion 22. The first connecting portion 25 has a generally rectangular shape in plan view extending in the left-right direction, and is formed to be narrower than the width of the battery-side terminal portion 22 (the length in the front-rear direction in FIG. 3A). The first connecting portion 25 has flexibility and is configured to be curved in an arc shape when the battery pack 1 described later is manufactured.

The first connecting portion 25 includes a first insulating base layer 46 and a connection wiring pattern 34 in the thickness direction.

The first insulating base layer 46 has the outer shape of the first connecting portion 25 and has a substantially rectangular shape in plan view.

A part of the connection wiring pattern 34, specifically, a fifth connection wiring 34e and a seventh connection wiring 34g described later are arranged on the other surface of the first insulating base layer 46 in the thickness direction.

The second connecting part 26 connects the control part 21 and the positive electrode terminal part 23, and is arranged on the rear side of the control part 21. Specifically, the second connecting portion 26 is arranged between these so that the front end thereof is continuous with the control portion 21 and the rear end thereof is continuous with the positive electrode terminal portion 23. The 2nd connection part 26 is formed in planar view substantially rectangular shape extended in the front-back direction.

A plurality of (four) second bending points 47 are formed in the front-rear direction at intervals in the front-rear direction of the second connecting portion 26. The second bent portion 47 extends linearly in the left-right direction from the left end edge to the right end edge. The front two of the second folding points 47 are configured to be bent at right angles toward the upper side, and the two rear portions of the second folding points 47 are allowed to be bent at right angles toward the lower side. It is configured.

The second connecting portion 26 includes a second insulating base layer 48 and a connection wiring pattern 34 in the thickness direction.

The second insulating base layer 48 has the outer shape of the second connecting portion 26 and has a substantially rectangular shape in plan view. A fifth via portion 49 for connecting the connection wiring patterns 34 to each other is formed in the second insulating base layer 48.

A part of the connection wiring pattern 34, specifically, a first connection wiring 34a, a second connection wiring 34b, an eighth connection wiring 34h, and a tenth connection wiring 34j described later are the thickness of the second base insulating layer 48. It is arranged on one surface in the direction and the other surface in the thickness direction.

The third connecting portion 27 connects the control portion 21 and the negative electrode terminal portion 24, and is arranged on the front side of the control portion 21. Specifically, the third connecting portion 27 is arranged between these so that the front end thereof is continuous with the negative electrode terminal portion 24 and the rear end thereof is continuous with the control portion 21. The third connecting portion 27 is formed in a generally rectangular shape in plan view extending in the front-rear direction.

A plurality of (two) third bending points 50 are formed at intervals in the front-rear direction in the middle of the third connecting portion 27 in the front-rear direction. The third bent portion 50 extends linearly in the left-right direction from the left end edge to the right end edge. The 3rd bending location 50 is comprised so that it can each bend at a right angle toward the lower side.

The third connecting portion 27 includes a third insulating base layer 51 and a connection wiring pattern 34 in the thickness direction.

The third insulating base layer 51 forms the outer shape of the third connecting portion 27 and has a substantially rectangular shape in plan view.

Part of the connection wiring pattern 34, specifically, a fourth connection wiring 34d, a sixth connection wiring f, and a ninth connection wiring 34i, which will be described later, are arranged on the other surface of the third insulating base layer 51 in the thickness direction. ing.

As shown in FIG. 3B, FIG. 4A, and FIG. 6, the coil unit 60 is a sheet coil and is a power receiving coil that receives power transmitted by a power transmitting device described later, and specifically, the power transmitting coil described later. It is a power receiving coil that can generate power by the magnetic field generated from the.

The coil portion 60 is arranged on the back surface side of the positive electrode terminal portion 23 so as to come into contact with the back surface of the positive electrode terminal portion 23. That is, the coil section 60 is arranged on the rear side of the control section 21. The coil portion 60 overlaps the positive electrode terminal portion 23 in the thickness direction, and is formed so as to have substantially the same shape as the outer shape of the positive electrode terminal portion 23 in a plan view.

The coil portion 60 includes the first coil cover insulating layer 61, the first coil pattern 62, the coil base insulating layer 63, the second coil pattern 64, and the second coil cover insulating layer 65 from the one side in the thickness direction to the other side. Prepare for the side.

The first coil cover insulating layer 61 is arranged on the back surface of the positive electrode terminal portion 23. The first coil cover insulating layer 61 has a substantially circular shape in a plan view and is formed to have a shape that is substantially the same as the outer shape of the positive electrode terminal portion 23.

As shown in FIG. 6, the first coil pattern 62 is arranged on the other surface (back surface) of the first coil cover insulating layer 61 in the thickness direction. Specifically, the first coil pattern 62 has a thickness of the first coil cover insulating layer 61 such that one surface in the thickness direction of the first coil pattern 62 contacts the other surface in the thickness direction of the first coil cover insulating layer 61. It is arranged on the other side of the direction. The first coil pattern 62 is a coil-shaped wiring pattern made of wiring.

As shown in FIG. 4, the first coil pattern 62 is formed in a spiral shape from the first coil via portion 66 (center in the radial direction) to the outside in the radial direction in a plan view. The first coil pattern 62 is formed in a spiral shape up to the outer peripheral end near the second connecting portion 26, and is connected (continuously) to the tenth connection wiring 34j at the outer peripheral end near the second connecting portion 26. ..

The side cross-sectional shape of the wiring forming the first coil pattern 62 along the radial direction is substantially rectangular as shown in FIG.

The coil base insulating layer 63 is arranged on the other side in the thickness direction of the first coil pattern 62. Specifically, the coil base insulating layer 63 is arranged on the other surface in the thickness direction of the first coil cover insulating layer 61 so as to cover the first coil pattern 62. The coil base insulating layer 63 forms the outer shape of the coil portion 60 and has a substantially circular shape in plan view. The coil base insulating layer 63 is formed to have substantially the same shape as the first coil cover insulating layer 61.

The second coil pattern 64 is arranged on the other surface of the coil base insulating layer 63 in the thickness direction. Specifically, the second coil pattern 64 is formed on the other surface in the thickness direction of the coil base insulating layer 63 so that one surface in the thickness direction of the second coil pattern 64 contacts the other surface in the thickness direction of the coil base insulating layer 63. It is arranged. The second coil pattern 64 is a coil-shaped wiring pattern made of wiring.

As shown in FIG. 3B, the second coil pattern 64 is formed in a spiral shape extending radially outward from the first coil via portion 66 in a bottom view. The second coil pattern 64 is formed in a spiral shape up to the outer peripheral end near the second connecting portion 26, and is connected to the first connection wiring 34a at the outer peripheral end near the second connecting portion 26.

The side cross-sectional shape of the wiring forming the second coil pattern 64 along the radial direction is substantially rectangular as shown in FIG.

The bottom view shape (spiral shape pattern) in the middle portion of the second coil pattern 64 is substantially the same as the plan view shape in the middle portion of the first coil pattern 62. That is, the width L of the wiring of the second coil pattern 64 and the spacing S between the wirings are substantially the same as the width L and the spacing S of the wiring of the first coil pattern 62, respectively, and the number of turns of the second coil pattern 64 is , And the number of turns of the first coil pattern 62 is the same.

In each of the first coil pattern 62 and the second coil pattern 64, the number of turns of the coil is, for example, 1 or more, preferably 3 or more, and is, for example, 500 or less, preferably 300 or less.

In each of the first coil pattern 62 and the second coil pattern 64, the width L (the radial length of the wiring) of the wiring is, for example, 5 μm or more, preferably 20 μm or more, and, for example, 400 μm or less, preferably Is 200 μm or less.

In each of the first coil pattern 62 and the second coil pattern 64, the spacing S between the wirings (radial distance between adjacent wirings) is, for example, 5 μm or more, preferably 20 μm or more, and, for example, It is 400 μm or less, preferably 200 μm or less.

The second coil cover insulating layer 65 is arranged on the other side in the thickness direction of the second coil pattern 64. Specifically, the second coil cover insulating layer 65 is arranged on the other surface in the thickness direction of the coil base insulating layer 63 so as to cover the second coil pattern 64.

The second coil cover insulating layer 65 has a substantially circular shape in a plan view, and when projected in the vertical direction, the second coil cover insulating layer 65 includes the second coil pattern 64.

A first coil via portion 66 is formed substantially in the center of the coil portion 60 in plan view. In the first coil via portion 66, a via opening portion that penetrates the coil base insulating layer 63 in the thickness direction is formed, and the metal conduction portion is filled in the via opening portion. The first coil via portion 66 is integrally continuous with the first coil pattern 62 and the second coil pattern 64, and electrically connects these.

A second coil via portion 67 is formed at the front end of the coil portion 60 in plan view. In the second coil via part 67, a via opening penetrating the coil base insulating layer 63 and the first coil cover insulating layer 61 in the thickness direction is formed, and the via conductive part is filled in the via opening. The second coil via portion 67 has one end face (upper end face) in the thickness direction contacting the positive electrode terminal portion 23, and the other end edge (lower end face) in the thickness direction is integrally continuous with the eighth connection wiring 34h. Connect electrically. That is, the positive electrode terminal portion 23 is electrically connected to the control portion 21.

Next, the connection wiring pattern 34 will be described with reference to FIGS. 3A-B and 4.

The connection wiring pattern 34 is wiring that electrically connects each terminal portion (22, 23, 24), each coil pattern (62, 64) and the control element 32. The connection wiring pattern 34 includes a first connection wiring 34a, a second connection wiring 34b, a third connection wiring 34c, a fourth connection wiring 34d, a fifth connection wiring 34e, a sixth connection wiring 34f, a seventh connection wiring 34g, and an eighth wiring. The connection wiring 34h, the ninth connection wiring 34i, and the tenth connection wiring 34j are provided.

As shown in FIG. 3B, the first connection wiring 34a electrically connects the rectifier 38 and the second coil pattern 64. That is, one end of the first connection wiring 34a is connected to the first via portion 35, and the other end is connected to the second coil pattern 64. Specifically, the first connection wiring 34a is arranged so as to reach from the front end of the coil portion 60 to the rear portion of the control portion 21 via the second connecting portion 26.

The second connection wiring 34b electrically connects the rectifier 38 and the first coil pattern 62 via the tenth connection wiring 34j and the fifth via portion 49. That is, one end of the second connection wiring 34 b is connected to the first via part 35, and the other end is connected to the fifth via part 49. Specifically, the second connection wiring 34b is arranged so as to extend from the rear portion of the control portion 21 to the center of the second coupling portion 26 in the front-rear direction.

The third connection wiring 34c electrically connects the rectifier 38 and the charge controller 39. That is, one end of the third connection wiring 34c is connected to the first via part 35, and the other end is connected to the second via part 36. Specifically, the third connection wiring 34c is arranged substantially in the center of the controller 21 in plan view.

The fourth connection wiring 34d electrically connects the rectifier 38 and the negative electrode terminal portion 24. That is, one end of the fourth connection wiring 34d is connected to the first via part 35, and the other end is connected to the negative electrode terminal part 24. Specifically, the fourth connection wiring 34d is arranged so as to reach the rear end of the negative electrode terminal portion 24 from the substantially center of the control portion 21 in plan view through the third connecting portion 27.

The fifth connection wiring 34e electrically connects the charging controller 39 and the battery side terminal portion 22. That is, one end of the fifth connection wiring 34 e is connected to the second via part 36, and the other end is connected to the fourth via part 43. Specifically, the fifth connection wiring 34e is arranged so as to reach the battery-side terminal portion 22 from the substantially center of the control portion 21 in plan view via the first connecting portion 25.

The sixth connection wiring 34f electrically connects the charging controller 39 and the negative electrode terminal portion 24. That is, one end of the sixth connection wiring 34f is connected to the second via portion 36, and the other end is connected to the negative electrode terminal portion 24. Specifically, the sixth connection wiring 34f is arranged so as to reach the rear end of the negative electrode terminal portion 24 from the substantially center of the control portion 21 in plan view through the second connecting portion 26.

The seventh connection wiring 34g electrically connects the transformer 40 and the battery side terminal portion 22. That is, one end of the seventh connection wiring 34g is connected to the third via part 37, and the other end is connected to the fourth via part 43. Specifically, the seventh connection wiring 34g is arranged so as to reach the battery-side terminal portion 22 from the substantially center in plan view of the control portion 21 via the first connection portion 25.

The eighth connection wiring 34h electrically connects the transformer 40 and the positive electrode terminal portion 23. That is, one end of the eighth connection wiring 34h is connected to the third via part 37, and the other end is connected to the second coil via part 67. Specifically, the eighth connection wiring 34h is arranged so as to reach the front end of the coil portion 60 from the substantially center of the control portion 21 in plan view via the second connection portion 26.

The ninth connection wiring 34i electrically connects the transformer 40 and the negative electrode terminal portion 24. That is, one end of the ninth connection wiring 34i is connected to the third via portion 37, and the other end is connected to the battery side negative terminal 45. Specifically, the ninth connection wiring 34i is arranged so as to reach the rear end of the negative electrode terminal portion 24 via the third connecting portion 27 from the right portion of the control portion 21.

As shown in FIGS. 3A and 4, the tenth connection wiring 34j electrically connects the rectifier 38 and the first coil pattern 62 via the fifth via portion 49 and the second connection wiring 34b.
That is, one end of the tenth connection wiring 34j is connected to the fifth via portion 49, and the other end is connected to the first coil pattern 62. Specifically, the tenth connection wiring 34j is arranged so as to extend from the center of the second connecting portion 26 in the front-rear direction to the coil portion 60.

The circuit board 20 is provided with a circuit cover insulating layer on one surface and the other surface in the thickness direction of the circuit board 20 so as to cover the connection wiring pattern 34 (see FIG. 5). That is, the circuit board 20 includes a circuit cover insulating layer which is arranged on one side or the other side in the thickness direction of each base insulating layer, corresponding to the connection wiring pattern 34. Specifically, the circuit cover insulating layer includes a lower circuit cover insulating layer 52 disposed on the other surface in the thickness direction of the base insulating layer and an upper circuit cover insulating layer (one side on the one surface in the thickness direction of the base insulating layer). (Not shown). The lower circuit cover insulating layer 52 is formed so as to cover the first connection wiring 34a to the ninth connection wiring 34i, and its rear end is continuous with the front end of the second coil cover insulating layer 65. The upper circuit cover insulating layer is formed so as to cover the tenth connection wiring 34j.

Examples of the insulating material of each insulating layer (33, 41, 46, 46, 51, 52, 61, 63, 65) include polyimide resin, polyamide-imide resin, acrylic resin, polyether nitrile resin, polyether sulfone resin, Examples thereof include synthetic resins such as polyethylene terephthalate resin, polyethylene naphthalate resin, and polyvinyl chloride resin, and preferably polyimide resin.

The thickness of each insulating layer is, for example, 1 μm or more, preferably 3 μm or more, and for example, 100 μm or less, preferably 50 μm or less.

Examples of the material of the conductive metal support that forms the positive electrode terminal portion 23 and the external negative electrode terminal 44 include metal materials such as stainless steel, 42 alloy, and aluminum. Preferably, stainless steel is used from the viewpoint of suppressing abrasion of these terminals and having excellent durability.

The thickness of the conductive metal support is, for example, 10 μm or more, preferably 15 μm or more, and for example, 200 μm or less, preferably 100 μm or less.

Examples of the material of the connection wiring pattern 34, the coil patterns (62, 64) and the terminals (42, 45) include conductive metals such as copper, silver, gold, nickel, solder and alloys thereof. Of these, copper is preferable.

The thickness of each of the connection wiring pattern 34, each coil pattern (62, 64) and each terminal (42, 45) is, for example, 3 μm or more, preferably 5 μm or more, and for example, 100 μm or less, preferably, It is 50 μm or less.

In such a board 3 with a coil, for example, the circuit board 20 excluding the control element 32 and the coil portion 60 are integrally formed by a subtractive method or an additive method, and then the control element 32 is mounted on the circuit board 20. It can be manufactured.

Specifically, a conductive metal support is prepared, a first insulating layer (first coil cover insulating layer 61, corresponding to the upper circuit cover insulating layer) is formed on the other surface in the thickness direction, and then, One conductor layer (corresponding to the first coil pattern 62, the battery side positive electrode terminal 42, the battery side negative electrode terminal 45, and the tenth connection wiring 34j) is provided on the other surface in the thickness direction of the first insulating layer and the conductive metal support. Then, a second insulating layer (corresponding to the

base insulating layers

33, 41, 46, 46, 51, 63) is formed, and then the first insulating layer and the conductive metal support are formed so as to cover the first conductive layer. Of the second conductor layer (corresponding to the first to ninth connection wirings 34a to 34i and the via portions 35 to 37, 43, 49, 66, 67) on the other surface in the thickness direction of the second insulating layer. On the other surface in the thickness direction of the second insulating layer so that the second conductor layer is covered with the third insulating layer (corresponding to the lower circuit cover insulating layer 52). To do. Thereafter, the conductive metal support is processed into the shapes of the positive electrode terminal portion 23 and the external negative electrode terminal 44 by etching or the like.

Next, on the mounting surface of the control unit 21, the control element 32 (rectifier 38, charge controller 39 and transformer 40) is mounted on the corresponding first to third via portions 35 to 37 via solder or the like. As a result, the control element 32 of the circuit board 20 is electrically connected to the first coil pattern 62 and the second coil pattern 64 of the coil portion 60 via the connection wiring pattern 34.

Next, the bending circuit 3A will be described with reference to FIGS. 2A-B, 3A-B and 7.

A bending circuit 3A is obtained by bending the first connecting portion 25, the second connecting portion 26, and the third connecting portion 27 of the substrate 3 with a coil.

Specifically, first, in the substrate 3 with a coil, the first connecting portion 25 is placed in a semicircle so that the terminal surface of the battery-side terminal portion 22 faces downward while maintaining the mounting surface of the control portion 21 on the upper side. Bend in an arc. As a result, the first connecting portion 25 becomes a curved portion. In addition, in the second connecting portion 26, the two front side second bent portions 47 are bent so as to form a right angle (valley fold) to the upper side and the rear side, respectively, and the two rear side first bent portions 47 are respectively bent to the upper side and the front side. The positive electrode terminal portion 23 and the coil portion 60 are arranged above the control portion 21 by bending so as to form a right angle (mountain folding). In addition, the two third bent portions 50 of the third connecting portion 27 are bent downward and rearward at right angles (mountain folds), respectively, and the negative electrode terminal portion 24 is arranged below the control portion 21.

Thereby, the bending circuit 3A in which the positive electrode terminal portion 23, the coil portion 60, the control portion 21, the battery side terminal portion 22, and the negative electrode terminal portion 24 are sequentially arranged from the upper side can be obtained.

In the bent circuit 3A, the contact surface of the positive electrode terminal portion 23, the mounting surface of the control portion 21, and the battery side negative electrode terminal 45 are arranged so as to face upward (to be the upper surface). Further, the terminal surface of the battery-side terminal portion 22 and the contact surface of the negative electrode terminal portion 24 are arranged so as to face downward (become the lower surface). That is, the battery side terminal portion 22 and the negative electrode terminal portion 24 in the state of the battery pack shown in FIG. 1A are different from the battery side terminal portion 22 and the negative electrode terminal portion 24 in the state of the developed view shown in FIGS. 3A and 3B, respectively. The vertical direction is reversed. The negative electrode terminal portion 24 is also inverted in the front-back direction.

The positive electrode terminal portion 23, the control portion 21, the battery side terminal portion 22, and the negative electrode terminal portion 24 are respectively arranged at intervals in the vertical direction and arranged in parallel in the surface direction (front-back direction or left-right direction). .. The coil portions 60 are arranged in parallel with each other in the plane direction such that the upper surface thereof contacts the lower surface of the positive electrode terminal portion 23. The first connecting portion 25 is arranged so as to extend in an arc shape from one end edge (left end edge) of the control portion 21 to the outside and below the control portion 21. The second connecting portion 26 extends upward from the rear end edge of the control portion 21, then bends and extends toward the front side, and then bends and extends toward the upper side. It is arranged so as to reach the front edge. The third connecting portion 27 is arranged so as to extend downward from the front end edge of the control portion 21 and reach the front end edge of the negative electrode terminal portion 24.

(Magnetic sheet)
As shown in FIGS. 2A-B and FIG. 7, the magnetic sheet 4 is arranged below the coil unit 60 and above the control unit 21. The magnetic sheet 4 has a flat plate shape that is substantially circular in plan view, and is formed to have substantially the same shape as the coil portion 60 in plan view.

The magnetic sheet 4 is a sheet containing a magnetic material, and examples thereof include a magnetic material particle-containing resin sheet and a magnetic material sintered sheet.

The magnetic material particle-containing resin sheet is formed into a sheet shape from a composition containing magnetic material particles and a resin component.

Examples of the magnetic substance forming the magnetic substance particles include a soft magnetic substance and a hard magnetic substance, and preferably a soft magnetic substance. As the soft magnetic material, for example, magnetic stainless steel (Fe—Cr—Al—Si alloy), sendust (Fe—Si—Al alloy), permalloy (Fe—Ni alloy), silicon copper (Fe—Cu—Si alloy), Fe-Si alloy, Fe-Si-B (-Cu-Nb) alloy, Fe-Si-Cr-Ni alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy, ferrite, etc. ..

Examples of the resin component include rubber polymers such as butadiene rubber, styrene-butadiene rubber, isoprene rubber, acrylonitrile rubber, polyacrylic acid ester, ethylene-vinyl acetate copolymer, and styrene acrylate copolymer. In addition to the above, as the resin component, for example, thermosetting resin such as epoxy resin, phenol resin, melamine resin, urea resin, for example, polyolefin, polyvinyl acetate, polyvinyl chloride, polystyrene, polyamide, polycarbonate, Examples thereof include thermoplastic resins such as polyethylene terephthalate.

The magnetic material sintered sheet is a sheet formed by sintering the above-mentioned magnetic material, and examples thereof include a ferrite sheet.

The thickness of the magnetic sheet 4 is, for example, 10 μm or more, preferably 50 μm or more, and for example, 500 μm or less, preferably 300 μm or less.

(Upper adhesive layer)
As shown in FIGS. 2A-B and 7, the upper adhesive layer 5 is disposed on the upper surface of the secondary battery 2, that is, the positive electrode surface 13. The upper adhesive layer 5 has a flat plate shape that is substantially circular in a plan view, and is formed to be smaller than the positive electrode surface 13 and the control section 21 in a plan view. The upper adhesive layer 5 is an insulating adhesive layer, and includes a first upper adhesive layer 71 and a second upper adhesive layer 72.

The first upper adhesive layer 71 is arranged substantially in the center of the upper adhesive layer 5 in a plan view, and has a substantially circular sheet shape in a plan view.

The first upper adhesive layer 71 is made of an insulating adhesive. Examples of the insulating adhesive include a pressure sensitive adhesive and a curable adhesive, and preferably a curable adhesive.

Examples of pressure-sensitive adhesives include acrylic pressure-sensitive adhesives and silicone pressure-sensitive adhesives.

Examples of the curable adhesive include an insulative curable composition which will be described later in the insulative resin fixing portion 7.

The elastic modulus of the first upper adhesive layer 71 is preferably lower than the elastic modulus of the second upper adhesive layer 72, and the thickness of the first upper adhesive layer 71 is preferably lower than the thickness of the second upper adhesive layer 72. thin.

The second upper adhesive layer 72 is arranged so as to surround the first upper adhesive layer 71, and has a substantially annular sheet shape in plan view. The inner peripheral edge of the second upper adhesive layer 72 coincides with the outer peripheral edge of the first upper adhesive layer 71.

The second upper adhesive layer 72 is made of an insulating adhesive. As the insulating adhesive, the above-mentioned pressure-sensitive adhesive is most preferable from the viewpoint of easy assembly.

The thickness of the second upper adhesive layer 72 is, for example, 5 μm or more, preferably 10 μm or more, and for example, 500 μm or less, preferably 200 μm or less.

(Lower adhesive layer)
As shown in FIGS. 2A-B and 7, the lower adhesive layer 6 is disposed on the lower surface of the secondary battery 2, that is, the negative electrode surface 14. The lower adhesive layer 6 has a flat plate shape that is substantially circular in plan view, is smaller than the negative electrode surface 14 in plan view, and is formed to have substantially the same shape as the negative electrode terminal portion 24. The lower adhesive layer 6 includes a first lower adhesive layer 73 and a second lower adhesive layer 74 as an example of the adhesive layer of the present invention.

The first lower adhesive layer 73 is a conductive adhesive layer, is disposed in the approximate center of the lower adhesive layer 6 in plan view, and has a substantially circular sheet shape in plan view. The composition and physical properties of the first lower adhesive layer 73 will be described in detail later.

The thickness of the first lower adhesive layer 73 is, for example, 5 μm or more, preferably 10 μm or more, and for example, 500 μm or less, preferably 200 μm or less.

The second lower adhesive layer 74 is arranged so as to surround the first lower adhesive layer 73, and has a substantially annular sheet shape in plan view. The inner peripheral edge of the second lower adhesive layer 74 coincides with the outer peripheral edge of the first lower adhesive layer 73.

The second lower adhesive layer 74 is made of an insulating adhesive. As the insulating adhesive, the pressure-sensitive adhesive described above is preferably used from the viewpoint of easy assembly.

The thickness of the second lower adhesive layer 74 is, for example, 5 μm or more, preferably 10 μm or more, and for example, 500 μm or less, preferably 200 μm or less.

(Insulating resin fixing part)
As shown in FIGS. 2A and 2B and FIG. 7, the insulating resin fixing portion 7 is arranged above the secondary battery 2 so as to embed a part of the coiled substrate 3. The insulating resin fixing portion 7 has a substantially columnar shape in a plan view and is formed so as to match the outer shape of the secondary battery 2 in a plan view.

The insulating resin fixing portion 7 is made of, for example, an insulating curable composition. Examples of the insulative curable composition include an insulative thermosetting composition, an insulative UV curable composition, an insulative moisture curable composition, and an insulative two-liquid mixed curable composition. Preferably, an insulating thermosetting composition is used. Thereby, the gap between the control elements 32 can be surely cured, and the strength of the battery pack 1 is excellent.

The insulating thermosetting composition contains a thermosetting resin.

Examples of the thermosetting resin include epoxy resin, phenol resin, melamine resin, vinyl ester resin, cyanoester resin, maleimide resin, silicone resin and the like. From the viewpoint of reliably sealing and fixing each member, an epoxy resin and a phenol resin are preferable, and a combination of an epoxy resin and a phenol resin is preferable.

The insulating thermosetting composition preferably further contains a thermoplastic resin from the viewpoint of exhibiting tackiness and suppressing positional displacement of each member.

Examples of the thermoplastic resin include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, Thermoplastic polyimide resin, polyamide resin (6-nylon, 6,6-nylon, etc.), phenoxy resin, acrylic resin, saturated polyester resin (PET, etc.), polyamideimide resin, fluororesin, styrene-isobutylene-styrene block copolymer And so on. An acrylic resin is preferable from the viewpoint of compatibility with a thermosetting resin and tackiness.

The proportion of the thermoplastic resin is, for example, 60 mass% or more, preferably 80 mass% or more, and for example, 99 mass% or less, preferably the total amount of the thermosetting resin and the thermoplastic resin. Is 95 mass% or less.

2. Details of First Lower Adhesive Layer The first lower adhesive layer 73 is made of a conductive adhesive and contains a resin and a conductive filler.

The resin is a cured resin (cured resin) in which the curable resin is completely cured (C stage). Examples of the curable resin include a thermosetting resin (for example, an epoxy resin, an acrylic resin, a silicone resin, an elastomer resin), an ultraviolet light curable resin, and the like. Such curable resins can be used alone or in combination of two or more kinds.

The curable resin preferably contains a thermosetting resin, more preferably an epoxy resin, and particularly preferably an epoxy resin.

The conductive filler is dispersed in the resin and imparts conductivity to the first lower adhesive layer 73. Examples of the conductive filler include metal particles such as copper, silver, gold, nickel and alloys thereof. Further, the conductive filler may be metal-coated resin particles obtained by coating resin particles with the above metal. Such conductive fillers can be used alone or in combination of two or more kinds.

The conductive filler preferably contains silver or a silver alloy, more preferably silver.

The shape of the conductive filler may be, for example, granular, scale-like, plate-like, needle-like, etc., preferably scale-like.

If the conductive filler has a scaly shape, the conductive filler can be oriented in a direction orthogonal to the thickness direction of the first lower adhesive layer 73, and the first lower adhesive layer is expanded and contracted by the secondary battery 2. Even if stress is applied to the layer 73, it is possible to reliably suppress fluctuations in the electric resistance of the first lower adhesive layer 73.

The average maximum length of the conductive filler is, for example, 0.1 μm or more, preferably 1 μm or more, for example, 50 μm or less, preferably 30 μm or less. The average maximum length of the conductive filler can be measured by SEM (scanning electron microscope) or TEM (transmission electron microscope).

When the average maximum length of the conductive filler exceeds the above upper limit, it is difficult to form a conductive path line in the first lower adhesive layer 73 because the conductive filler is less likely to contact. Therefore, when stress is applied to the first lower adhesive layer 73, there is a high probability that the conduction path cannot be taken. On the other hand, by setting the average maximum length of the conductive filler within the above range, the conduction state can be secured in the first lower adhesive layer 73.

The content ratio of the conductive filler in the first lower adhesive layer 73 is, for example, 30% by mass or more, preferably 50% by mass or more, for example, 90% by mass or less.

When the content ratio of the conductive filler is within the above range, the tensile storage elastic modulus of the first lower adhesive layer 73 can be reliably adjusted to the range described below, and the first lower adhesive layer 73 has conductivity. Can be surely given.

The volume resistance value of the first lower adhesive layer 73 is, for example, 0 Ω·cm or more, for example, 10×10 ⁰ Ω·cm or less, preferably 1×10 ⁰ Ω·cm or less, and further preferably 1 ×10 ⁻³ Ω·cm or less. The volume resistance value can be measured by a 4-terminal 4-probe method or a double ring method.

If the volume resistance value of the first lower adhesive layer 73 is less than or equal to the above upper limit, efficient charging/discharging of the secondary battery 2 can be ensured.

Such a first lower adhesive layer 73 has a tensile storage elastic modulus E′ at 23° C. under the following measurement conditions of 1 GPa or more, preferably 3 GPa or more, more preferably 5 GPa or more, for example, 500 GPa or less, preferably Is 100 GPa or less. The measurement conditions for the tensile storage elastic modulus are that the test method is DMA (tensile mode), the frequency is 1 Hz, and the temperature rising rate is 10° C./min (the same applies hereinafter).

If the tensile storage elastic modulus of the first lower adhesive layer 73 is equal to or higher than the above lower limit, even if the secondary battery 2 expands and contracts when the secondary battery 2 is charged and discharged, the conductive filler is dispersed in the resin. It is possible to suppress the change of the state, and thus suppress the change of the electric resistance of the first lower adhesive layer 73. In addition, if the tensile storage elastic modulus of the first lower adhesive layer 73 is equal to or less than the above upper limit, mechanical properties and reliability can be secured. On the other hand, when the tensile storage elastic modulus of the first lower adhesive layer 73 exceeds the above upper limit, the first lower adhesive layer 73 becomes brittle, and mechanical characteristics and reliability cannot be ensured.

The first lower adhesive layer 73 has a peel strength in a 90° peel test of, for example, 0.10 N/5 mm or more, preferably 0.15 N/5 mm or more, for example, 100 N/5 mm or less, preferably 50 N. /5 mm or less.

The peel strength of the first lower adhesive layer 73 can be measured by the following method.

First, as the raw material of the first lower adhesive layer 73, a conductive curable adhesive containing the raw material of the above resin (that is, the resin in the A stage state) and the above conductive filler is prepared. Then, the conductive curable adhesive is sandwiched between a gold-plated copper plate (Au-plated copper plate) and a nickel-plated stainless plate (Ni-plated SUS), and cured at 50° C. for 10 hours. As a result, a sample in which an adhesive layer having a width of 5 mm adheres the Au-plated copper plate and the Ni-plated SUS is prepared. Then, the peel strength of the first lower adhesive layer 73 is measured by measuring the load when peeling the Au-plated copper plate from the Ni-plated SUS under the conditions of a peel angle of 90° and a peel speed of 10 mm/min. it can.

3. Assembly of Battery Pack Assembly (manufacturing) of the battery pack 1 will be described with reference to FIGS. 8A-E and 9F-H. Assembling the battery pack 1 includes, for example, a preparing step, a bending step, an arranging step, a curing step, a joining step, and an adhering step.

[Preparation process]
In the preparation step, the secondary battery 2, the coiled substrate 3, and the magnetic sheet 4 are prepared. Insulating adhesives (insulating pressure-sensitive adhesives and insulating curable adhesives), conductive curable adhesives, and a plurality of insulating thermosetting sheets 110 are also prepared.

A plurality (two) of insulating thermosetting sheets 110 are each formed into a sheet shape from the above-mentioned insulating thermosetting composition. The insulating thermosetting sheet 110 has a circular shape in plan view. The insulating thermosetting sheet 110 has a shape that is larger than, substantially the same shape as, or smaller than the coil portion 60, and preferably has a small shape, in plan view.

[Bending process]
In the bending step, as shown in FIG. 8A, the second connecting portion 26 of the substrate with coil 3 is bent.

Specifically, while maintaining the mounting surface of the control unit 21 on the upper side, the two front side second bending portions 47 are bent so as to form a right angle (valley fold) to the upper side and the front side, respectively. The positive electrode terminal portion 23 and the coil portion 60 are arranged above the control portion 21 by bending the vicinity of the second bent portion 47 so as to form a right angle (mountain fold) to the upper side and the rear side, respectively. On the other hand, the first connecting portion 25 and the third connecting portion 27 are not bent in this step.

By this, a partially bent circuit 3B is obtained in which a part is bent.

[Placement process]
In the arranging step, as shown in FIG. 8B, the magnetic sheet 4 and the insulating thermosetting sheet 110 are arranged in the partially bent circuit 3B.

First, the magnetic sheet 4 is placed on the partially folded circuit 3B. Specifically, the magnetic sheet 4 is arranged on the lower surface of the coil portion 60. At this time, if necessary, the magnetic sheet 4 may be adhered to the lower surface of the coil portion 60 via an insulating adhesive layer or the like.

Next, the insulating thermosetting sheet 110 is placed inside the partially folded circuit 3B. Specifically, a plurality (two) of insulating thermosetting sheets 110 are inserted between the control section 21 and the second connecting section 26 and between the coil section 60 and the second connecting section 26. ..

As a result, the first intermediate body 101 including the partially bent circuit 3B, the magnetic sheet 4, and the insulating thermosetting sheet 110 is obtained.

[Curing process]
In the curing step, as shown in FIGS. 8C-D, the first intermediate body 101 is heated while being compressed.

First, as shown in FIG. 8C, a first intermediate body 101, a support plate 112, a release film 113, a spacer 114 and a pressing plate 115 are prepared, and these are arranged in order.

The spacer 114 is a member for adjusting the insulating resin fixing portion 7 of the first intermediate body 101 to a desired shape, and has a through hole 116 penetrating the spacer 114. The through hole 116 has a substantially circular shape in a plan view, and is formed to have a substantially same shape as the secondary battery 2 in a plan view. The thickness of the spacer 114 is substantially the same as the thickness of the insulating resin fixing portion 7 in the obtained battery pack 1.

Next, as shown in FIG. 8D, the pressing plate 115 is pressed toward the support plate 112 so that the first intermediate body 101 and the central portion of the release film 113 are housed in the through holes 116 of the spacer 114. To do.

Next, as shown in FIG. 8E, a heating process is performed. As a result, the insulating thermosetting sheet 110 is melted and cured.

Specifically, the insulating thermosetting sheet 110 is spread in the surface direction, covers the mounting surface of the control unit 21, the lower surface of the coil unit 60, and the entire surface of the second connecting unit, and simultaneously cures.

By this, the insulating resin fixing portion 7 which is a cured body of the insulating thermosetting sheet 110 is formed. At this time, the insulating thermosetting sheet 110 spreads outward in the surface direction by heating and pressing, and covers (embeds) the entire circumference of the second connecting portion 26.

As a result, as shown in FIG. 9F, the second intermediate body 102 including the partially bent circuit 3B, the magnetic sheet 4, and the insulating resin fixing portion 7 is obtained.

[Joining process]
In the joining step, as shown in FIG. 9G, the terminal surface of the battery-side terminal portion 22 is joined to the positive electrode surface 13 of the secondary battery 2.

As a joining method, a known method as an electrical connecting method can be mentioned, and preferably a metal joining can be mentioned.

The metal joining includes, for example, fusion joining and soldering, preferably soldering. Thereby, the battery-side terminal portion 22 and the secondary battery 2 can be firmly electrically connected.

As a result, the third intermediate body 103 including the partially bent circuit 3B, the magnetic sheet 4, the insulating resin fixing portion 7 and the secondary battery 2 is obtained.

[Adhesion process]
In the bonding step, as shown in FIG. 9H, the control section 21 is bonded to the positive electrode surface 13 of the secondary battery 2 by using the upper bonding layer 5 (upper bonding step), while the negative electrode terminal section 24 is lowered. The side adhesive layer 6 is used to adhere to the negative electrode surface 14 of the secondary battery 2 (lower side adhesion step).

(1) In the upper bonding step, the upper bonding layer 5, that is, the first upper bonding layer 71 and the second upper bonding layer 72 are arranged on the positive electrode surface 13 of the secondary battery 2.

The arrangement of each upper adhesive layer 5 includes, for example, a method of applying a liquid state (A stage) adhesive, a method of attaching a sheet (adhesive tape, etc.) made of a pressure sensitive adhesive, and the like.

Preferably, an adhesive sheet made of an insulating pressure-sensitive adhesive is used as the material for the second upper adhesive layer 72, and the sheet is attached to the positive electrode surface 13 to arrange the second upper adhesive layer 72 first. Then, the first upper adhesive layer 71 is arranged in the second upper adhesive layer 72 using an insulating curable adhesive in a liquid state (A stage). As a result, the second upper adhesive layer 72 functions as a dam, so that the first upper adhesive layer 71 can be easily arranged in the center of the positive electrode surface 13 using the liquid adhesive.

Next, the third intermediate body 103 is bent so that the upper surface of the upper adhesive layer 5 contacts the back surface of the control unit 21. Specifically, the first connecting portion 25 is curved in an arc shape so that the mounting surface of the control portion 21 faces upward. As a result, the first connecting portion 25 becomes a curved portion. The first connecting portion 25 projects outward from the left end of the secondary battery 2 when projected in the vertical direction. After that, the insulating curable adhesive in the liquid state (A stage) is cured (in the C stage state).

By this, the control unit 21 is fixed to the secondary battery 2 via the upper adhesive layer 5.

(2) In the lower adhesive step, first, the lower adhesive layer 6, that is, the first lower adhesive layer 73 and the second lower adhesive layer 74 are arranged on the negative electrode surface 14 of the secondary battery 2.

The arrangement of each lower adhesive layer 6 includes, for example, a method of applying a liquid state (A stage) adhesive, a method of attaching a sheet (adhesive tape, etc.) made of a pressure-sensitive adhesive, and the like.

Preferably, as the material of the second lower adhesive layer 74, an adhesive sheet made of an insulating pressure-sensitive adhesive is used, and this sheet is attached to the negative electrode surface 14, whereby the second lower adhesive layer 74 is formed first. Then, the first lower adhesive layer 73 is placed in the second lower adhesive layer 74 by using the conductive curable adhesive in the liquid state (A stage). As a result, the second lower adhesive layer 74 functions as a dam, so that the first lower adhesive layer 73 can be easily arranged in the center of the negative electrode surface 14 by using the liquid adhesive.

The liquid conductive curable adhesive contains the above-mentioned resin raw material (A stage resin) and the above-mentioned conductive filler. The viscosity of the conductive curable adhesive in the liquid state is, for example, 500 mPa·s or more and 500,000 mPa·s or less at 25°C.

Next, the third intermediate body 103 is bent so that the back surface of the negative electrode terminal portion 24 contacts the bottom surface of the lower adhesive layer 6. Specifically, the two second bent portions 47 of the third connecting portion 27 are bent so as to form a right angle (mountain fold) to the lower side and the front side, respectively, and the negative electrode terminal portion 24 is arranged below the control portion 21. ..

After that, the conductive curable adhesive in liquid state (A stage) is cured (in C stage state). More specifically, when the above-mentioned resin is a cured product of a thermosetting resin, the liquid conductive curable adhesive is applied, for example, at 23° C. or higher and 150° C. or lower, for example, for 15 minutes or more and 96 hours or less. Heat to cure.

As a result, the first lower adhesive layer 73 is formed, and the negative electrode terminal portion 24 (battery-side negative electrode terminal 45) is electrically connected to the secondary battery 2 via the first lower adhesive layer 73. , The lower adhesive layer 6 (specifically, the first lower adhesive layer 73 and the second lower adhesive layer 74) is fixed to the secondary battery 2. That is, the first lower adhesive layer 73 bonds the negative electrode surface 14 of the secondary battery 2 and the battery-side negative electrode terminal 45 of the circuit board 20.

When the lower adhesive layer 6 is arranged, the secondary battery 2 may be turned upside down and the negative electrode surface 14 may be temporarily arranged so as to be the upper side.

In this way, the battery pack 1 is obtained.

4. Battery Pack In the battery pack 1, as shown in FIGS. 1A-B, 2A-B, and 7, the secondary battery 2 includes a coiled substrate 3, a magnetic sheet 4, an upper adhesive layer 5, a lower adhesive layer 6, and The insulating resin fixing portion 7 is arranged. Specifically, on the upper side of the secondary battery 2, the positive electrode terminal portion 23, the coil portion 60, the insulating resin fixing portion 7, the magnetic sheet 4, the second connecting portion 26, the control portion 21, the battery side terminal portion 22, and The upper adhesive layer 5 is disposed, the lower adhesive layer 6 and the negative electrode terminal portion 24 are disposed below the secondary battery 2, and the third connecting portion 27 is disposed on the peripheral side surface of the secondary battery 2. Are arranged.

The positive electrode terminal portion 23 is located at the uppermost end of the battery pack 1 and is arranged so that its contact surface is on the upper side. The positive electrode terminal portion 23 overlaps the coil portion 60, the magnetic sheet 4, and the positive electrode surface 13 when projected in the vertical direction. In the positive electrode terminal portion 23, the side surface is in contact with the insulating resin fixing portion 7, and the center of the lower surface is in contact with the upper surface of the coil portion 60.

The coil portion 60 is arranged below the positive electrode terminal portion 23 and above the magnetic sheet 4. In the coil portion 60, the upper surface contacts the lower surface of the positive electrode terminal portion 23, the side surface contacts the insulating resin fixing portion 7, and the lower surface contacts the upper surface of the magnetic sheet 4 and the insulating resin fixing portion 7.

The magnetic sheet 4 is arranged below the coil unit 60 and above the control unit 21. In the magnetic sheet 4, the upper surface contacts the lower surface of the coil portion 60, and the side surfaces and the lower surface contact the insulating resin fixing portion 7.

The second connecting portion 26 is arranged between the positive electrode terminal portion 23 and the control portion 21 in a folded state from the front end edge of the positive electrode terminal portion 23 to the rear end edge of the control portion 21. The entire periphery of the second connecting portion 26 is covered with the insulating resin fixing portion 7.

The control unit 21 is arranged below the magnetic sheet 4 and the second connecting unit 26 and above the upper adhesive layer 5. In the controller 21, the upper surface (mounting surface) and the side surface contact the insulating resin fixing portion 7, and the lower surface contacts the upper surface of the upper adhesive layer 5. In other words, the control unit 21 is arranged above the positive electrode surface 13 with the positive electrode surface 13 of the secondary battery 2 vertically spaced apart from the positive electrode surface 13 by an interval 75, and in the distance 75, the upper adhesive layer 5 and the battery side terminal. The part 22 is arranged.

The insulating resin fixing portion 7 is arranged in the vertical direction from the positive electrode terminal portion 23 to the control portion 21. The insulating resin fixing portion 7 is arranged so as to substantially match the outer shape of the secondary battery 2 in plan view in plan view.

The insulating resin fixing portion 7 covers the side surface and the lower surface of the positive electrode terminal portion 23, the coil portion 60, and the magnetic sheet 4, covers the entire surface of the second connecting portion 26, and covers the side surface and the upper surface of the control portion 21. The upper peripheral edge surface and the side surface of the insulating resin fixing portion 7 are exposed from the battery pack 1.

The maximum thickness of the insulating resin fixing portion 7 is, for example, 0.6 mm or more, preferably 1 mm or more, and for example, 4 mm or less, preferably 3 mm or less.

The first connecting portion 25 (curved portion) is arranged so as to extend from the control portion 21 to the positive electrode terminal portion 23 in the vertical direction. The first connecting portion 25 is arranged so as to project outward from the insulating resin fixing portion 7. That is, the first connecting portion 25 projects from the secondary battery 2 when projected in the vertical direction. The protruding portion protruding from the insulating resin fixing portion 7 in the first connecting portion 25 has a semicircular arc shape in a side view. Specifically, the protrusion has a substantially U-shape so as to protrude in the radial direction.

The battery-side terminal portion 22 is arranged below the control portion 21 and above the positive electrode surface 13. Specifically, the battery-side terminal portion 22 is arranged below the control portion 21 with a space in the vertical direction from the control portion 21. The battery-side terminal portion 22 is arranged so that the terminal surface faces downward, and the terminal surface contacts the positive electrode surface 13.

The upper adhesive layer 5 is arranged below the control unit 21 and above the positive electrode surface 13. In the upper adhesive layer 5, the upper surface contacts the lower surface (rear surface) of the control unit 21, and the lower surface contacts the positive electrode surface 13. The upper adhesive layer 5 is included in the control unit 21 and the positive electrode surface 13 when projected in the vertical direction. Since the upper adhesive layer 5 is arranged in the space 75 between the control unit 21 and the positive electrode surface 13 so as to be in contact with them, it serves as a support member that supports the control unit 21 from below.

The secondary battery 2 is arranged above the upper adhesive layer 5 and above the lower adhesive layer 6. The positive electrode surface 13 contacts the lower surface of the upper adhesive layer 5 and the terminal surface of the battery-side terminal portion 22, and the negative electrode surface 14 contacts the lower adhesive layer 6. As a result, the positive electrode surface 13 of the secondary battery 2 is electrically connected to the coiled substrate 3 via the battery side terminal portion 22, and the negative electrode surface 14 via the lower adhesive layer 6 and the negative electrode terminal portion 24. And is electrically connected to the coiled substrate 3. Further, the secondary battery 2 is fixed to the coiled substrate 3 via the upper adhesive layer 5 and the lower adhesive layer 6.

The lower adhesive layer 6 is arranged below the secondary battery 2 and above the negative electrode terminal portion 24. In the lower adhesive layer 6, the upper surface contacts the negative electrode surface 14, and the lower surface contacts the battery-side negative electrode terminal 45 of the negative electrode terminal portion 24. The lower adhesive layer 6 is included in the negative electrode terminal portion 24 and the negative electrode surface 14 when projected in the vertical direction.

The negative electrode terminal portion 24 is located at the lowermost end of the battery pack 1 and is arranged such that its contact surface is on the lower side. The negative electrode terminal portion 24 is arranged below the lower adhesive layer 6 so as to come into contact with the lower surface of the lower adhesive layer 6.

The third connecting portion 27 is arranged on the front side of the battery pack 1. The third connecting portion 27 is arranged on the front side of the secondary battery 2 so as to come into contact with the front side peripheral side surface of the secondary battery 2 in the vertical center between the control portion 21 and the negative electrode terminal portion 24.

4. Wireless Power Transmission System An embodiment of the wireless power transmission system of the present invention will be described with reference to FIG.

The wireless power transmission system 80 includes the battery pack 1 and a power transmission device 81.

The power transmission device 81 includes a power transmission coil 82, an oscillation circuit 83, and an external power supply connection means 84.

The power transmission coil 82 includes, for example, the above-mentioned coil unit 60, for example, a winding coil formed by winding a wire material such as a copper wire.

The oscillation circuit 83 is a circuit that generates electric power having a frequency of 1 MHz or more and 10 MHz or less (preferably 1 MHz or more and 5 MHz or less). The oscillator circuit 83 may be, for example, any of an LC oscillator circuit system, a CR oscillator circuit system, a crystal oscillator circuit system, and a switching circuit system.

The external power supply connection means 84 is a means that can be connected to the external power supply 85, and examples thereof include an AC adapter and a USB terminal.

Power transmission by a magnetic field between the coil unit 60 (power receiving coil) and the power transmitting coil 82 may be performed by either a magnetic field resonance method or an electromagnetic induction method. Preferably, the magnetic field resonance method is used from the viewpoint that the transmission distance can be increased and that electric power can be transmitted with high efficiency even when the axis of the coil is displaced.

5. Charging/Discharging Mechanism Referring to FIGS. 2A-B, 3A-B and FIG. 10, the mechanism of charging and discharging locations of the wireless power transmission system 80 will be described.

(When charging)
The electric power supplied to the oscillation circuit 83 by the external power supply 85 is converted into electric power having a frequency of, for example, 1 MHz or more and 10 MHz or less, and the magnetic field is generated from the power transmission coil 82 by the electric power of the frequency. The coil unit 60 (power receiving coil) receives the power of the frequency by the magnetic field generated by the power transmitting coil 82.

The received electric power is converted into direct current by the control element 32 and controlled to a voltage lower than a predetermined value, and the secondary battery 2 is supplied with electric power. That is, for example, an alternating current of 1 MHz or more and 10 MHz or more is generated in the coil portion 60, and the alternating current passes through (1) the first connection wiring 34a or (2) the tenth connection wiring 34j and the second connection. It is converted into direct current by the rectifier 38 via the wiring 34b. Then, the direct current reaches the charging controller 39 via the third connection wiring 34c. After that, the direct current controlled by the charge controller 39 reaches the positive electrode surface 13 of the secondary battery 2 via the fifth connection wiring 34e and the battery side terminal portion 22. On the other hand, on the negative electrode side, from the negative electrode surface 14 (ground) of the secondary battery 2, the lower adhesive layer 6 (first lower adhesive layer 73), the negative electrode terminal portion 24 (battery negative electrode terminal 45) and the sixth connection wiring. The current reaches the charging controller 39 via 34f.

This will charge the secondary battery 2.

(During discharge)
A current having a predetermined voltage (for example, 3.7V) is discharged from the positive electrode surface 13 of the secondary battery 2, and the current passes through the battery-side terminal portion 22 and the seventh connection wiring 34g and then the transformer 40. To reach. Then, the transformer 40 transforms a current having a predetermined voltage into a desired voltage (for example, 1.2 V). Then, the transformed current is passed through the eighth connection wiring 34h and the positive electrode terminal portion 23 to a positive electrode terminal (for example, an external device positive electrode terminal 96 described later) of an external electronic device (for example, a hearing aid 90 described later). To reach. On the other hand, on the negative electrode side, the negative electrode terminal of the external electronic device (for example, an external device negative electrode terminal 97 described later) is passed through the negative electrode terminal portion 24 (the external negative electrode terminal 44 and the battery negative electrode terminal 45) and the lower adhesive layer 6. Then, the current reaches the negative electrode surface 14 (ground) of the secondary battery 2, and the current reaches the transformer 40 via the negative electrode terminal portion 24 and the ninth connection wiring 34i.

This causes the secondary battery 2 to discharge and drive external electronic devices.

The battery pack 1 and the wireless power transmission system 80 as described above can be widely used for electronic devices using conventional secondary batteries and primary batteries. Examples of such electronic equipment include wearable terminals such as hearing aids, smart glasses, and smart watches, such as speakers, and medical equipment.

In the battery pack 1, as shown in FIG. 2A, the first lower adhesive layer 73 for adhering the negative electrode surface 14 of the secondary battery 2 and the battery-side negative terminal 45 of the circuit board 20 to the tensile storage above the lower limit. It has an elastic modulus.

Therefore, when the secondary battery 2 is charged and discharged, even if the secondary battery 2 expands and contracts and stress is applied to the first lower adhesive layer 73, the dispersed state of the conductive filler in the resin may change. It is possible to suppress, and consequently, it is possible to suppress fluctuation in the electric resistance of the first lower adhesive layer 73.

As a result, it is possible to improve the connection reliability between the negative electrode surface 14 of the secondary battery 2 and the battery-side negative electrode terminal 45 of the circuit board 20, while ensuring stable charging/discharging of the secondary battery 2. ..

Further, the first lower adhesive layer 73 preferably has a peel strength not lower than the above lower limit. Therefore, even if the secondary battery 2 expands and contracts, the battery-side negative electrode terminal 45 of the circuit board 20 can be suppressed from peeling from the negative electrode surface 14 of the secondary battery 2. As a result, it is possible to surely improve the connection reliability between the negative electrode surface 14 of the secondary battery 2 and the battery-side negative electrode terminal 45 of the circuit board 20.

The thickness of the first lower adhesive layer 73 is preferably within the above range. Therefore, it is possible to more reliably improve the connection reliability between the negative electrode surface 14 of the secondary battery 2 and the battery-side negative electrode terminal 45 of the circuit board 20, while the battery pack 1 can be downsized.

The volume resistance value of the first lower adhesive layer 73 is preferably the above upper limit or less. Therefore, efficient charging/discharging of the secondary battery 2 can be ensured.

The resin contained in the first lower adhesive layer 73 preferably contains an epoxy resin (completely cured (C stage) epoxy resin). Therefore, the tensile storage elastic modulus of the first lower adhesive layer 73 can be reliably adjusted within the above range.

The content ratio of the conductive filler in the first lower adhesive layer 73 is preferably the above lower limit or more. Therefore, while the tensile storage elastic modulus of the first lower adhesive layer 73 can be reliably adjusted within the above range, conductivity can be reliably imparted to the first lower adhesive layer 73.

The conductive filler contained in the first lower adhesive layer 73 preferably has a scaly shape. Therefore, the conductive filler can be oriented in a direction orthogonal to the thickness direction of the first lower adhesive layer 73, and even if stress is applied to the adhesive layer due to expansion and expansion of the secondary battery 2, the first lower adhesive layer It is possible to reliably suppress fluctuations in the electric resistance of the layer 73.

Also, the average maximum length of the conductive filler is preferably less than or equal to the above upper limit.

However, if the average maximum length of the conductive filler exceeds the above upper limit, the conductive filler line is unlikely to come into contact with the first lower adhesive layer 73, which makes it difficult to form a conductive path line. Therefore, when stress is applied to the first lower adhesive layer 73, there is a high probability that the conduction path cannot be taken. On the other hand, when the average maximum length of the conductive filler is equal to or less than the above upper limit, the conductive state can be secured in the first lower adhesive layer 73.

The battery pack 1 also includes a coil unit 60 arranged above the secondary battery 2 and electrically connected to the circuit board 20. Therefore, the coil unit 60 can receive power from the external power transmission coil 82. As a result, the secondary battery 2 can be wirelessly powered.

Further, since the wireless power transmission system 80 is provided with the battery pack 1 having excellent connection reliability and capable of ensuring stable charging/discharging of the secondary battery 2, stable wireless charging of the secondary battery 2 is possible.

5. Hearing Aid Next, one embodiment of the hearing aid of the present invention will be described with reference to FIGS. 11A-B.

The hearing aid 90 includes the battery pack 1, a hearing aid housing 91, a microphone means 92, an amplifying means 93, a speaker section 94, an external device positive electrode terminal 96 and an external device negative electrode terminal 97.

As the transformer 40 mounted on the battery pack 1 used for the hearing aid 90, for example, a transformer capable of transforming to 1.2V is used.

The hearing aid housing 91 has a housing body 91A and an opening/closing mechanism 91B.

The casing main body 91A houses therein a microphone means 92, an amplifying means 93, a speaker portion 94, an external device positive electrode terminal 96, and an external device negative electrode terminal 97.

The external device positive electrode terminal 96 and the external device negative electrode terminal 97 are arranged to face each other with a space therebetween under the casing main body 91A. The distance between the tip of the external device positive electrode terminal 96 (contact point with the positive electrode terminal portion 23) and the tip of the external device negative electrode terminal 97 (contact point with the negative electrode terminal portion 24) is the vertical length of the battery pack 1 (see FIG. 2A)).

The microphone unit 92, the amplification unit 93, and the speaker unit 94 are arranged inside the hearing aid housing 91, and these are electrically connected to the external device positive electrode terminal 96 and the external device negative electrode terminal 97.

The opening/closing mechanism section 91B is arranged at the lower end of the housing body section 91A. The opening/closing mechanism part 91B is a curved plate member having an arc shape in a side view and a U-shape in a front view, and one end (fixed end part) 98 of the opening/closing mechanism part 91B is provided at a lower end of the housing body part 91A via a hinge part. And is rotatably fixed. The opening/closing mechanism portion 91B forms a housing portion 95 together with the space between the external device positive electrode terminal 96 and the external device negative electrode terminal 97.

The accommodation portion 95 has a space capable of accommodating the battery pack 1. The accommodating portion 95 is configured to selectively accommodate the battery pack 1 or a commercially available primary battery (preferably a button type primary battery).

The housing part 95 is housed inside the hearing aid housing 91 or exposed to the outside by rotating the opening/closing mechanism part 91B with the fixed end part 98 as a fulcrum. Specifically, as shown in FIG. 11A, by moving the free end portion 99 (the other end opposite to the fixed end portion 98) of the opening/closing mechanism portion 91B toward the lower side, the accommodating portion 95 is exposed to the outside. Exposed to (open state). On the other hand, as shown in FIG. 11B, by moving the free end portion 99 upward, the housing portion 95 is housed inside the hearing aid housing 91 (closed state).

When the opening/closing mechanism section 91B is in the open state, the upper part of the housing section 95 is open, and the battery pack 1 can be replaced. On the other hand, when the opening/closing mechanism unit 91B is in the closed state, the size and shape of the inside of the housing unit 95 are substantially the same as the size and shape of the battery pack 1.

The battery pack 1 is housed in the housing section 95. Specifically, in the battery pack 1, as shown in FIG. 11B, when the opening/closing mechanism unit 91B is in the closed state, the external device positive electrode terminal 96 is in contact with the positive electrode terminal unit 23, and the external device negative electrode terminal 97 is in contact. , Is arranged inside the housing portion 95 so as to contact the negative electrode terminal portion 24.

The hearing aid 90 includes the battery pack 1, a hearing aid housing 91, a microphone means 92, an amplifying means 93, and a speaker section 94. Therefore, the hearing aid 90 can be downsized, and in particular, the housing portion 95 can be downsized. Further, since the battery pack 1 includes the first lower adhesive layer 73 that can prevent the dispersed state of the conductive filler from changing even when stress is applied, the hearing aid 90 is housed in the housing portion 95 of the battery pack 1, When the external device positive electrode terminal 96 is brought into contact with the positive electrode terminal portion 23 to be charged/discharged, it is possible to prevent the electric resistance of the first lower adhesive layer 73 from changing due to expansion of the secondary battery 2 or the like. Therefore, the secondary battery 2 can be stably charged and discharged, and the occurrence of defective charging of the secondary battery can be suppressed.

In this hearing aid 90, the accommodating portion 95 can also accommodate a primary battery. Therefore, since it can be driven by using either the primary battery or the secondary battery, it is excellent in convenience.

6. Modification of One Embodiment In each modification below, the same members and steps as those in the above-described embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In addition, each modified example can achieve the same operational effect as that of the embodiment except for the special mention. Furthermore, each modification can be combined appropriately.

(1) In the embodiment shown in FIGS. 1A and 3A, the positive electrode terminal portion 23 does not have a through hole, but, for example, the positive electrode terminal portion 23 has a through hole such as a slit as shown in FIG. May be.

In the embodiment shown in FIG. 12, a plurality of slits 120 are formed in the positive electrode terminal portion 23.

The plurality of slits 120 are formed radially from the central portion 121 of the positive electrode terminal portion 23 to the peripheral edge.

The plurality of slits 120 includes a plurality of (two types) slits (long slits 122, short slits 123) having different radial lengths. The plurality (two types) of

slits

122 and 123 are formed alternately at equal intervals in the circumferential direction.

Preferably, the embodiment shown in FIG. 12 can be mentioned. In this embodiment, when the magnetic force from the power transmission coil passes through the positive electrode terminal portion 23, the generation of eddy current in the positive electrode terminal portion 23 can be suppressed. Therefore, the phenomenon that the magnetic force generated by the eddy current cancels the magnetic force from the power transmission coil can be suppressed. Therefore, a decrease in power reception efficiency can be suppressed.

The shape and number of the through holes are not limited and can be changed as appropriate.

(2) In the embodiment shown in FIGS. 1A and 2A, the coil portion 60 is arranged such that the upper surface thereof contacts the lower surface of the positive electrode terminal portion 23. However, for example, the coil portion 60 includes the positive electrode terminal portion 23. It is also possible to arrange them with a space in the vertical direction.

In this embodiment, a development view of the coiled substrate 3 is shown in, for example, FIGS. 13A and 13B. In the substrate 3 with a coil shown in FIGS. 13A and 13B, the coil portion 60 and the positive electrode terminal portion 23 are arranged in different directions in a plan view with the control portion 21 as the center. The coiled substrate 3 further includes a fourth connecting portion 28 that connects the control portion 21 and the coil portion 60. By folding the two fourth bending portions 53 of the fourth connecting portion 28, in the bending circuit 3A, the coil portion is provided at an intermediate position between the control portion 21 and the positive electrode terminal portion 23 in the up-down direction and at an interval in the up-down direction. 60 are arranged.

Preferred examples include the embodiments shown in FIGS. 1A and 2A. As a result, when the battery pack 1 is manufactured (in particular, the step of bending the substrate 3 with a coil), the positional deviation between the positive electrode terminal portion 23 and the coil portion 8 can be suppressed, and the variation in characteristics between products can be suppressed. it can.

Further, the relative arrangement of the coil unit 60 and the control unit 21 is not limited, and for example, although not shown, the coil unit 60 may be arranged below the control unit 21.

(3) In the board with coil 3 shown in FIGS. 13A and 13B, the battery pack 1 includes the board with coil 3 in which the coil portion 60 and the circuit board 20 are integrally formed. The coil portion 60 and the circuit board 20 may be composed of separate members.
In this embodiment, the coil part 60 includes a plurality of (two) terminals for electrically connecting with the circuit board 20, and the circuit board 20 has a plurality of (2) terminals for electrically connecting with the coil part 60. One) and electrically connect these terminals.

(4) In the embodiment shown in FIG. 2A and FIG. 2B, only the negative electrode surface 14 of the secondary battery 2 and the battery-side negative electrode terminal 45 of the circuit board 20 have a conductive adhesive layer (first lower adhesive layer 73). Although not shown, for example, the positive electrode surface 13 of the secondary battery 2 and the battery-side positive electrode terminal 42 of the circuit board 20 may be bonded by an adhesive layer having conductivity.

In this case, the battery-side positive electrode terminal 42 is provided on the surface opposite to the mounting surface of the control circuit board 31, and the first upper adhesive layer 71 is formed from the same conductive adhesive as the first lower adhesive layer 73. .. As a result, the positive electrode surface 13 of the secondary battery 2 and the battery-side positive electrode terminal 42 of the circuit board 20 can be bonded by the conductive adhesive layer having the above-mentioned tensile storage elastic modulus.

(5) In the embodiment shown in FIGS. 2A and 2B, the coil unit 60 and the control unit 21 are provided on the upper side of the secondary battery 2, but the vertical arrangement of these is not limited, and for example, the coil unit 60 is The secondary battery 2 may be arranged on the upper side, the lower side, or both sides of the secondary battery 2, and the control unit 21 may be arranged on the upper side, the lower side, or both sides of the secondary battery 2.

(6) In the embodiment shown in FIGS. 1A and 6, the coil part 60 has the first coil pattern 62 or the second coil pattern 64. For example, although not shown, the coil part 60 has the first coil pattern 62. Alternatively, only one of the second coil patterns 64 may be included.

Further, the substrate with coil 3 includes one coil portion 60, but, for example, although not shown, the substrate with coil 3 (bending circuit 69) may include a plurality of coil portions 60. The number and arrangement of the plurality of coil portions 60 are not limited, and for example, a plurality of coil portions 60 may be provided on the upper side of the secondary battery 2, or a plurality of coil portions 60 may be provided on the lower side of the secondary battery 2. A single battery or a plurality of batteries may be provided on both sides of the secondary battery 2.

(7) In the embodiment shown in FIG. 1A and FIG. 5, the negative electrode terminal portion 24 includes only the battery side negative electrode terminal 45 and the external side negative electrode terminal 44. A negative electrode conductive layer and a negative electrode insulating layer may be further provided. That is, the negative electrode terminal portion 24 may include the battery side negative electrode terminal 45, the negative electrode conductive layer, the negative electrode insulating layer, and the external side negative electrode terminal 44 in this order in the vertical direction. The negative electrode conductive layer and the negative electrode insulating layer have substantially the same planar shape as the battery side negative electrode terminal 45, and the negative electrode insulating layer includes a via portion electrically connecting the negative electrode conductive layer and the external side negative electrode terminal 44. As a result, the battery side negative electrode terminal 45 is electrically connected to the external side negative electrode terminal 44 via the negative electrode conductive layer and the via portion of the negative electrode insulating layer.

In this embodiment, the mechanical strength of the negative electrode terminal portion 24 is excellent.

(8) In the embodiment shown in FIGS. 1A and 4A, the circuit board 20 includes the rectifier 38, the charge controller 39, and the transformer 40 as the control element 32. Can also include an element (for example, an integrated circuit) in which two or three of the rectifier 38, the charge controller 39, and the transformer 40 are combined as one member. In addition, the circuit board 20 may further include other elements such as a capacitor for suppressing noise as the control element 32. The connection wiring pattern 34 and the via portions (35 to 37, 43, 49) are appropriately changed according to the type and number of the control elements 32.

(9) In the embodiment shown in FIGS. 1A and 2A, the battery pack 1 includes the magnetic sheet 4, but, for example, although not shown, the battery pack 1 may not include the magnetic sheet 4. From the viewpoint of power reception efficiency, the battery pack 1 preferably includes the magnetic sheet 4.

(10) In the embodiment shown in FIGS. 1A and 2A, the secondary battery 2 includes the positive electrode tab 12, but, for example, although not shown, the battery pack 1 may not include the positive electrode tab 12. .. In this case, the upper surface of the battery body 11 becomes the positive electrode surface 13.

Also, the secondary battery 2 can be provided with a negative electrode tab on the lower surface thereof. In this case, the lower surface of the negative electrode tab becomes the negative electrode surface 14.

(11) In the embodiment shown in FIGS. 1A and 2A, the insulating resin fixing portion 7 is exposed, but for example, although not shown, the battery pack 1 has a housing covering the insulating resin fixing portion 7. Further provisions can be made.

(12) In the embodiment illustrated in FIGS. 2A and 2B, the case where the resin contained in the first lower adhesive layer 73 is a completely cured product of a curable resin has been described in detail. The resin contained in the layer 73 may be a thermoplastic resin as long as the tensile storage elastic modulus of the first lower adhesive layer 73 is 1 GPa or more.

(13) In the embodiment shown in FIGS. 8A-E, the insulating resin fixing portion 7 is arranged by using the insulating thermosetting sheet 110. For example, although not shown, liquid resin sealing, resin The insulating resin fixing portion 7 may be arranged by inserting a molded product or the like.

Even with such a modified example, it is possible to obtain the same operational effects as the above-described embodiment. Further, the above-described embodiments and modified examples can be combined as appropriate.

The present invention will be described more specifically below with reference to reference examples and reference comparative examples. The present invention is not limited to the reference examples and reference comparative examples. In addition, specific numerical values such as a blending ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned "Description of Embodiments", and a corresponding blending ratio ( Content ratio), physical property values, parameters, etc. may be replaced with the upper limit (values defined as “below” or “less than”) or the lower limit (value defined as “greater than or equal to” or “exceeded”). it can.

<Reference example>
A conductive curable adhesive containing an epoxy resin raw material (epoxy resin in the A stage state) and silver (conductive filler) was prepared. The conductive curable adhesive was liquid at 25° C., and the content ratio of the conductive filler in the conductive curable adhesive was 50 to 90 mass %.

Next, on the gold-plated copper plate (Au-plated copper plate), an insulating adhesive layer having an annular shape was formed from the insulating pressure-sensitive adhesive. The insulating adhesive layer had a thickness of 100 μm, and the insulating adhesive layer had an inner diameter of 4500 μm.

Then, after injecting a conductive curable adhesive into the insulating adhesive layer, a nickel plate is applied to the conductive curable adhesive from the opposite side of the Au-plated copper plate to a stainless steel plate (Ni plated SUS). Was placed, and the conductive curable adhesive was sandwiched between the Au-plated copper plate and the Ni-plated SUS.

After that, the conductive curable adhesive was cured at 50° C. for 10 hours. The thickness of the conductive adhesive layer formed from the conductive curable adhesive was 100 μm.

Thus, a sample was prepared in which the adhesive layer including the conductive adhesive layer and the insulating adhesive layer adhered the Au-plated copper plate and the Ni-plated SUS.

The tensile storage elastic modulus of the cured conductive adhesive layer at 23° C. was 6 GPa.

<Reference comparative example>
A sample was prepared in the same manner as in the reference example except that the epoxy resin raw material (epoxy resin in the A stage state) was changed to the silicone resin raw material (silicone resin in the A stage state).

The tensile storage elastic modulus at 23° C. of the conductive adhesive layer after curing was 0.225 GPa.

<Mechanical stress-dependent measurement of electrical resistance>
The above-mentioned samples were set to electric resistance measurement values, and changes in electric resistance of each sample were observed while pressing Ni-plated SUS toward the adhesive layer at a speed of 7 μm/s with a micrometer. The result of the sample of the reference example is shown in FIG. 14A, and the result of the sample of the reference comparative example is shown in FIG. 14B.

As shown in FIGS. 14A and 14B, it was confirmed that in the sample of the reference example, the variation in electric resistance was significantly suppressed as compared with the sample of the reference comparative example.

Although the above-described invention is provided as an exemplary embodiment of the present invention, this is merely an example and should not be limitedly interpreted. Modifications of the invention that will be apparent to those skilled in the art are within the scope of the following claims.

The battery pack and the wireless power transmission system of the present invention are used, for example, in electronic devices such as hearing aids.

1 Battery Pack 2 Secondary Battery 13 Positive Surface 14 Negative Surface 20 Circuit Board 73 First Lower Adhesive Layer 80 Wireless Power System 90 Hearing Aid

Claims

A secondary battery having a positive electrode surface on the upper surface and a negative electrode surface on the lower surface,
A circuit board having a terminal electrically connected to the secondary battery,
An adhesive layer for adhering the positive electrode surface and/or the negative electrode surface to the terminal,
The adhesive layer includes a resin and a conductive filler dispersed in the resin,
The battery pack, wherein the adhesive layer has a tensile storage elastic modulus at 23° C. of 1 GPa or more.
The battery pack according to claim 1, wherein the adhesive layer has a peel strength of 0.15 N/5 mm or more in a 90° peel test.
The battery pack according to claim 1, wherein the thickness of the adhesive layer is 5 μm or more and 500 μm or less.
The battery pack according to claim 1, wherein the volume resistance value of the adhesive layer is 1×10 0 Ω·cm or less.
The battery pack according to claim 1, wherein the resin includes an epoxy resin.
The battery pack according to claim 1, wherein the content ratio of the conductive filler in the adhesive layer is 50% by mass or more.
The battery pack according to claim 1, wherein the conductive filler has a scaly shape.
The battery pack according to claim 1, wherein the average maximum length of the conductive filler is 30 μm or less.
The battery pack according to claim 1, further comprising a coil portion arranged on the upper side and/or the lower side of the secondary battery and electrically connected to the circuit board.
A wireless power transmission system comprising the battery pack according to claim 9 and a power transmission device including a power transmission coil.
A battery pack according to claim 9;
A hearing aid housing having a housing for housing the battery pack,
A hearing aid, comprising: a microphone means, an amplification means, and a speaker section provided inside the hearing aid housing.